I find the lid ones are worse because you can't see immediately if the litter needs changing.

If you've got 3 cats and one tray, you are going to need to change the litter a lot.

You know that you have no hope in hell of containing poo smell. I changed mine on to dry food and the smell is MUCH better than when they were on whiskas. TBH whiskas smells much the same pre-digestion.

There is an absorbing crystal type litter which I liked in terms of reducing the smell, but it was too expensive and couldn't cope with the volume of wee.

Ok so I somehow ended up with 3 cats So I purchased one of those litter trays with the lid on thinking it would hide the smell more than the open trays, turns out it doesn't and I can't always empty out there mess as id be sat next to it all day everyday, the filters are completely useless , Surely somebody knows how to combat the smell